1. Field of the Invention
The invention relates to trailers, and more particularly to trailers having hydraulic lift assemblies.
2. Description of the Related Art
Trailers are used to haul a variety of items, e.g., cars, all terrain vehicles, and boats. Boat trailers include both float trailers and cantilevered trailers. Float trailers do not actively move boats. Instead, boats are loaded on and unloaded from float trailers by backing the trailer down a boat ramp into enough water to float the boat onto and off the trailer.
Cantilevered trailers actively raise and lower boats with, e.g., a hydraulic lift system. Cantilevered trailers can raise and lower boats into and out of the water typically by a winch and pulley lift assembly or by a hydraulic lift assembly. A cantilevered trailer with winch and pulley lift assembly requires manual operation of the winch and pulley system to raise and lower the trailer, fatiguing an operator when multiple lifts are required. This problem particularly affects people, such as boat dealers, that raise and lower many boats a day. In addition, informed people find raising and lowering even a single boat difficult. In addition, trailers with winch and pulley systems take time to operate the winch.
Furthermore, winch and pulley systems are permanently mounted to the trailers, requiring the replacement of the entire trailer when a problem occurs with the winch and pulley system and, conversely, disposal of the winch and pulley system when the trailer is worn out.
Cantilevered trailers equipped with hydraulic lift assemblies are advantageous over those equipped with winch and pulley systems in that they are mechanized. A typical conventional trailer with hydraulic lift assembly has a hydraulic ram positioned between an upper and a lower frame of the trailer. Such positioning of the hydraulic ram has several drawbacks. For example, a hydraulic pump typically is located far from the hydraulic ram, requiring the use of long hydraulic hoses to connect the pump to the ram. Furthermore, when the hydraulic ram is positioned between the two frames of the trailer, the hydraulic ram is submerged when the trailer is backed down a ramp into water. Such submersion causes problems related to corrosion.
Thus, there is a need for a trailer that has a hydraulic lift assembly that avoids at least some of the problems noted above. In particular, the trailer should have a hydraulic ram that is kept out of the water during use. The trailer should have hydraulic conduits of a sufficiently short length such that they do not tangle with each other or other components of the trailer. Furthermore, there is a need for a hydraulic lift system that can be easily transferred from one trailer to another and/or that can be easily retrofitted onto an existing trailer.
The invention, which is defined by the claims set out at the end of this disclosure, is intended to solve at least some of the problems noted above. It is also applicable in applications other than boat hauling, in which there is a need to raise and lower vehicles and to haul vehicles.
In accordance with a first aspect of the invention, a trailer includes a tongue, an upper frame, a lower frame coupled to the upper frame via a plurality of arms and from which the tongue extends, and a lift assembly. The lift assembly includes 1) a hydraulic ram and 2) a hydraulic pump that is operatively connected to the hydraulic ram. The hydraulic ram raises the upper frame to a raised position when the hydraulic ram is retracted, and lowers the upper frame to a lowered position when the hydraulic ram is extended.
A lift assembly is provided that includes a ram stand, a hydraulic ram that is mounted on the ram stand, and a hydraulic pump that is operatively connected to the hydraulic ram. The lift assembly is configured to be attachable to a upper frame of a trailer. The hydraulic ram lifts the upper frame of the trailer to a raised position when the hydraulic ram is retracted, and lowers the upper frame to a lowered position when the hydraulic ram is extended.
Also provided is a method of raising and lowering a trailer. In the method, an upper frame of the trailer is raised by retracting a hydraulic ram that is connected to the upper frame. The upper frame of the trailer is lowered by extending the hydraulic ram.